Nonclassical two-photon interference between independent telecommunication light pulses converted by difference-frequency generation

Two-photon absorption of nonclassical light.

Photon entanglement signatures in difference-frequency-generation.

In response to quantum optical fields, pairs of molecules generate coherent nonlinear spectroscopy signals. Homodyne signals are given by sums over terms each being a product of Liouville space pathways of the pair of molecules times the corresponding optical field correlation function. For classical fields all field correlation functions may be factorized and become identical products of field...

Generation of narrow-bandwidth tunable picosecond pulses by difference- frequency mixing of stretched pulses

We propose what is, to our knowledge, a novel method of generating tunable narrow-bandwidth picosecond pulses in which the chirp of equally stretched pump and signal is canceled by difference-frequency mixing. The effect of the group-velocity mismatch on the output pulse bandwidth is analyzed. The method is proved experimentally by generation of pulses of 3.3-cm21 bandwidth and 10-ps duration i...

Postselective two-photon interference from a continuous nonclassical stream of photons emitted by a quantum dot.

We report an electrically driven semiconductor single-photon source capable of emitting photons with a coherence time of up to 400 ps under fixed bias. It is shown that increasing the injection current causes the coherence time to reduce, and this effect is well explained by the fast modulation of a fluctuating environment. Hong-Ou-Mandel-type two-photon interference using a Mach-Zehnder interf...

Stationary two-atom entanglement induced by nonclassical two-photon correlations

A system of two two-level atoms interacting with a squeezed vacuum field can exhibit stationary entanglement associated with nonclassical two-photon correlations characteristic of the squeezed vacuum field. The amount of entanglement present in the system is quantified by the well known measure of entanglement called concurrence. We find analytical formulas describing the concurrence for two id...